Hundreds of thousands of grandparents who look after their grandchildren could be given parental rights to paid leave and greater financial support, David Cameron has said.

The Prime Minister highlighted how more than 200,000 grandparents are getting a “raw deal” after stepping in to look after children whose parents have died, fallen ill or are unable to provide adequate care themselves.

He said the Conservatives will consider making a pledge in its manifesto for the general election to give grandparents who look after their children the same rights as adoptive parents. From next year, adoptive parents will be entitled to nine months of paid leave.

Mr Cameron revealed that he had considered plans to pay grandparents for looking after children under the Government’s child care voucher system, but said the scheme was dropped because it would have been too complicated and open to abuse.

The comments reflect the Conservatives’ desire to win the support of more than 1.9 million “unsung heroes”, who save Britain more than £7 billion in child care costs by looking after their grandchildren.

Mr Cameron said at an event in north London: “You do see sometimes grandparents stepping in and effectively bring up children, and of course under the rules they don’t get quite the same set of rights as others. What you are saying is that if you can extend to adoptive parents things that birth parents have in terms of rights, couldn’t you do that for grandparents?

“That is something I am very happy to look at in terms of manifesto, and we have got some Conservative MPs here who have got some responsibility for giving me ideas on that front, so I am sure they will take note of it.”

Mr Cameron also announced measures to help families stay together. He said that, for too long, politicians have been reluctant to talk about the issue because they are “far from perfect” themselves. He committed the Government to doubling the funding for counselling services and announced that 500,000 families will come under the troubled families programme.

Experts estimate that more than 200,000 grandparents become their grandchildren’s carers when parents die, become ill or because of drug and alcohol abuse. They are often unwilling to adopt or foster the children because they do not want to “paint the parent out of the picture”.

Sam Smethers, chief executive of the charity Grandparents Plus, welcomed the announcement. She said research shows that grandparents are “unsung heroes and they do a brilliant job for these kids”.

She added: “The vast majority of those children will have better outcomes than they would have [had they] gone into the care system.

“We know of quite a lot of families where, over a period, and it can be a long period of time, there is reunification and parents do come back into a child’s life. It can mean that a relationship that could have been severed may be repaired.”

Martin Narey, chief executive of Barnardos, said: “I welcome this focus on an extraordinary and selfless group of people.”

Women are entitled to nine months of paid leave and three months of unpaid leave after they give birth, a right that will be extended to adoptive parents.

Campaigners want paid parental leave to be extended to grandparents, as well as four to six weeks of unpaid leave during the “crisis” period while children are settling in and are being kept out of care.

Last year a pensioner won the right to be treated as her grandson’s foster mother. The woman from Derbyshire, 68, who has been looking after the 13-year-old since he was a baby, went to the High Court after learning she would receive twice as much financial support if she was a stranger.

Most local authorities do not automatically class grandparents who look after children as foster carers and therefore they are not entitled to the full range of benefits.